Source: US. Bureau of Labor Statistics
Release: Employment Situation
The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNU03032222
US. Bureau of Labor Statistics, Unemployment Level: Natural Resources, Construction, and Maintenance Occupations [LNU03032222], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/LNU03032222, July 26, 2016.